Mammal

Mammals are a class of vertebrate animals scientifically known as the Mammalia. They are primarily characterized by the presence of mammary glands in the female which produce milk to feed their young, which (except in the case of the Monotremata which lay eggs), are born live. Mammals are warm-blooded and most are hairy.

Evolutionary scientists frequently claim that the first true mammals appeared in the early Jurassic.